30th April 2024

A 55-year-old man presents with sudden onset of severe pain in his right wrist following a weekend of gardening.

A 55-year-old man presents with sudden onset of severe pain in his right wrist following a weekend of gardening. The wrist is swollen, red, and warm to the touch. He denies any recent trauma or fever. On examination, the wrist shows limited range of motion due to pain.

Investigations:

Haemoglobin: 160 g/L (135–180)

White cell count: 10.2 × 10⁹/L (4.0–11.0)

CRP: 40 mg/L (<5)

ESR: 30 mm/hr (0–15)

Which is the most appropriate investigation to achieve a diagnosis?